1.Field of the Invention
The invention is directed to polymeric compositions, particularly to thermoplastic compositions which comprise nylons, and more particularly to flexible thermoplastic compositions comprising nylon.
2.Description of the Prior Art
The use of polymeric materials in engineered material applications is a field of continuing and growing importance as new applications for such materials induce a commensurate growth for new types of materials with improved properties or suited for a particular need.
One such area of growth in is in the area of rubbery thermoplastic polymeric materials which have physical properties which approximate elastomers, and which may be produced and formed into useful articles using conventional methods. Such thermoplastic materials which comprise nylon 6 and which are flexible and are partially elastomeric in character are well known. Such materials are discussed in "Rubber-Thermoplastic Compositions. Part IX. Blends of Dissimilar Rubbers and Plastics with Technological Compatibilization" by A. Y. Coran, R. Patel and D. Williams-Headd published in Rubber Chemistry and Technology, Vol. 58, p.1014 (1985), and in "Rubber-Thermoplastic Compositions. Part II. NBR-Nylon Thermoplastic Elastomeric Compositions." by A. Y. Coran and R. Patel published in Rubber Chemistry and Technology, Vol. 53, p.781 (1980). These references describe thermoplastic elastomeric materials which include polyamide/nitrile rubbers, and include polyamides, with further constituents such as ethylene/acrylic acid, ethylene/vinyl acetate copolymers and epichlorohydrin and polyureathane as well. In the production of such compositions, the elastomeric or "rubber-phase" are cured through the addition of a curing agent which is added to the compositions during melt blending of the polymer composition prior to subsequent processing.
Further thermoplastic polymeric materials which feature physical properties which approximate elastomers include those which are described in European Patent Application 341,731 which comprise a thermoplastic resin which may be a polyester, polyamide, copolyetherester, or copolyetheramide which forms less than 30 weight percent of the total composition, 50-89 weight percent of an acid containing ethylene copolymer, and 1-22 weight percent of a glycidyl containing copolymer. The compositions described therein are formable in a two-step process, wherein the thermoplastic resin is first reacted with the glycidyl containing copolymer, and the reaction product is then reacted with the acid containing ethylene copolymer. The resultant compositions may be used to form articles by conventional molding procedures.